The invention relates to molds for manufacturing new tires and molds for retreading tires. More particularly, the invention relates to a device for easily releasing a removable plate from a hot mold.
Such pocket plates are inserts for a mold side wall ring that are used to mold information onto a tire sidewall, for example, tire brand information or a bar code for inventory identification. A mold side wall ring may be used over a relatively long period of time, and for molding different versions of a single tire model. The removable plates are changed when the information on the plate needs to be changed for different tire molding requirements.
In conventional molds, pocket plates are held in place in a mold by magnets, by screws fastened from the front of the plate, or by screws fastening the plates from the back of the side wall ring. In the case of magnets, when the mold is heated, the side wall ring and plate expand, which provides friction to help hold the plate in place.
The conventional means of holding pocket plates in side wall rings present drawbacks. In molds in which the plates are fastened with front attaching screws, the screw heads leave a mark on the molded tire. When the screws are fastened from the back of the plate, the mold must be first removed from the press to gain access to the screws. Once the plate is changed, the mold must be reinstalled and realigned in the press, which involves time and effort. The magnet fastened plates must be allowed to cool before they can be removed, which causes delay, and additionally are difficult to grasp for removal because of the lack of an edge or grip on the surface of the plate.
The present invention provides a device for quickly and easily removing pocket plates from a mold. According to the invention, a mold half has a recess to receive a pocket plate. A rod inserted in a hole in a mold half part, a first end of the rod being disposed at an accessible outer surface of the mold half part, a second end of the rod disposed in a position adjacent to the pocket plate recess. The rod is movable in the hole and includes a cam surface that is selectably moved into the recess to push on the pocket plate by movement of the rod.
According to another aspect of the invention, the rod is rotatable in the hole and the cam is radially arranged on the rod for movement upon rotation. In addition, the second end include a hook radially opposite the cam surface for engaging a catch on the back surface of the pocket plate to secure the pocket plate in the recess.
According to an alternative embodiment of the invention, the rod is slidable in the hole, and the cam is linearly arranged on the second end of the rod. The rod includes a tab that engages a slot in the pocket plate to selectably secure the pocket plate in the recess.